Liquid/solid phase transfer activation of Grubbs-type alkene metathesis catalysts; application of silver salts of sulfonated polystyrene

Alkene metatheses catalyzed by (H(2)IMes)(Cy2PCH2CH2N(CH3)(3)(+))-(Cl)(2) Ru(=CHPh) Cl-, an analog of Grubbs' second generation catalyst with an ammonium-salt containing phosphine, are dramatically accelerated when conducted in the presence of the insoluble resin PS-SO3Ag (PS = polystyrene). A mechanism involving ionic and covalent phosphine binding (PS-SO3Ag . PCy2CH2CH2N(CH3)(3)(+) PS-SO3 (-)) with concomitant formation of AgCl is proposed. Grubbs' second generation catalyst exhibits a modest rate enhancement, believed to reflect the generation of PS-SO3Ag.PCy3.